Abstract
OBJECTIVES: Paradoxical associations between high occupational physical activity (OPA) and cardiovascular disease may be explained by exaggerated cardiovascular responses from high work-related stress or low worker fitness. METHODS: OPA, blood pressure (BP), heart rate (HR), and rate-pressure product (RPP; HR × BP) were measured objectively for 24 hours in 19 male workers. Work-related stress was measured using the Stress in General Scale. Fitness was estimated using a submaximal treadmill test. Effect modification by work-related stress and fitness on associations between OPA and cardiovascular responses was examined using mixed models with interactions. RESULTS: Associations between OPA and RPP, HR, and BP were stronger with high stress ( P < 0.05). Associations of work-time moderate and vigorous physical activity and RPP were attenuated with higher fitness ( P < 0.05). CONCLUSIONS: OPA performed under high work-related stress or by workers with low fitness may exaggerate cardiovascular responses to OPA.